PC educational software needed

Hello:
I am currently looking for some educational software for the kids,
teenagers and adults learning centre. I would like to know which
programs are the best to use and where I can download those complete
set of programs. Anyone who has information about this, please help
me out. Thank in advanced.
1.) English courses:
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** Level: from kindergarten to high school
** Dos & windows version
2.) Mathematics courses:
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** Level: from kindergarten to high school
** Dos & windows version
3.) Computer courses:
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** Introduction to personal computer.
Basic ideas of how to operate windows and simple DOS
commands.
** If anyone have related programs for sale, please feel free
to contact me. Thank you very much.
Eugene.
e-mail: cs911196 at ariel.cs.yorku.ca